Real fame at last: Connolley dissekerer en af Frank Lansners og mine udvekslinger........

"However, Huybers' [2005] simulations do not fully emulate MBH98 methodology, as his simulations did not replicate the effect of a proxy network.
"

"The apparent contradiction between verification statistics is thus fully resolved: the cross-validation R2 of ~0.0 demonstrates that the MBH98 model is statistically insignificant; the new simulations, implementing the variance re-scaling called for by Huybers and newly-revealed in the MBH98 code, confirm our earlier finding that the seemingly high MBH98 RE statistic is spurious."

Frank Lansner skrev:
SRJ,

Se figur 2, her har du min kilde:
http://climateaudit.files.wordpress.com/2009/12/nas-mm.pdf

Se også figur 7.

kulden-varmen skrev:

Kristoffer Haldrup skrev:

kulden-varmen skrev:

kfl skrev:
Begge grafer er blevet falsificeret. Tekst er ganske simplet noget vrøvl og fordrejninger.

Er dette ikke også vrøvl og fordrejninger?!

Hvis man ville, kunne man finde opdateringer til graferne - men det gider/vil man selvfølgelig ikke.

Nej du gider heller ikke. :-)
Det forstår jeg godt for Jeg kender godt den graf som hedder ishockeystaven. Men så længe at du ikke kan indse at ishockeystaven er vrøvl og fordrejninger, så længe kan vi ikke komme videre i debatten.

Hvad er det for en "ishockeystav" du snakker om?

http://en.wikipedia.org/wiki/Hockey_stick_controversy
Og denne ishockeystav mener du at du aldrig har hørt om? Hel sikker?

Er det sådan en som den her:

http://www.arcus.org/synthesis2k/synthesis/index.php

-Og i givet fald, hvad mener du, at der er "løgn og fordrejninger" ved den rekonstruktion af temperaturen?

Problemet er at træers årringe ikke uden videre kan bruges til at bestemme temperaturen. Hvis skoven bliver mørkere så bliver årringene smallere. Og tilsvarende ved tørke og pluslig varme. Kraftig frugtsætning kan også give smalle årringe. Dels har nogle træer flere kromosom set end to, og de vokser ikke i takt med de andre træer.

"der findes bogstaveligt talt BUNKER af temperatur-rekonstruktioner, som alle i store træk ligner hinanden: Mere eller mindre fladt forløb henover de sidste par tusinde år, og en skarp stigning i det 20. "

Kristoffer Haldrup skrev:
Tak fordi du svarer så forudsigeligt. Jeg spurgte som jeg gjorde for at understrege det faktum at der ikke findes "een ishockeystav" -- der findes bogstaveligt talt BUNKER af temperatur-rekonstruktioner, som alle i store træk ligner hinanden: Mere eller mindre fladt forløb henover de sidste par tusinde år, og en skarp stigning i det 20. århundrede. Og den tidslige udvikling ser man, uanset om man bruger træer, iskerner eller sø/hav-sedimenter.

Kristoffer Haldrup skrev:
Tak fordi du svarer så forudsigeligt. Jeg spurgte som jeg gjorde for at understrege det faktum at der ikke findes "een ishockeystav" -- der findes bogstaveligt talt BUNKER af temperatur-rekonstruktioner, som alle i store træk ligner hinanden: Mere eller mindre fladt forløb henover de sidste par tusinde år, og en skarp stigning i det 20. århundrede. Og den tidslige udvikling ser man, uanset om man bruger træer, iskerner eller sø/hav-sedimenter.

Pointen er, at IPCC med deres 2001 raport pludseligt melder meget markant ud at der ikke er nogen MWP, og de fokuserer pludseligt på Manns suspekte graf.
Det er pointen, og så kan man vælge at fokusere på alt muligt andet.

....the posited Medieval Warm Period appears to have been less distinct, more moderate in amplitude, and somewhat different in timing at the hemispheric scale than is typically inferred for the conventionally-defined European epoch [Lambs graf, CBH]. The Northern Hemisphere mean temperature estimates of (Jones et al. 1998), (Mann et al. 1999), and (Crowley & Lowery 2000) show temperatures from the 11th to 14th centuries to be about 0.2°C warmer than those from the 15th to 19th centuries, but rather below mid-20th century temperatures.

CLAIM #6 "[Michael Mann] has claimed that there was no Medieval warm period"

THE REALITY: Ummm, I've written dozens of papers about the "Medieval Warm Period" (or what scientists in my field generally now refer to as the "Medieval Climate Anomaly", because of the considerable regional complexity of the climate anomaly during that time period). Indeed, I devote a fair amount of space to in my book "The Hockey Stick & the Climate Wars" (http://bit.ly/sRasaq) discussing some of the enigmatic features of this period and the work that I and other climate scientists have been focused on, for example investigations of why the tropical Pacific seems to have been in a "La Nina"-like state at that time (see e.g. our '09 Science article: http://www.meteo.psu.edu/~mann/shared/research/mannetal_science09/mannetal_science09.html), with possible implications for understanding climate change impacts on drought (see e.g. our recent PNAS article "1,500 year quantitative reconstruction of winter precipitation in the Pacific Northwest"; http://www.pnas.org/content/early/2012/06/25/1201083109.abstract?sid=58550d3c-f348-431e-9277-6a1e0e69eb83) what the Northern Hemisphere jet stream was doing at the time (see: http://www.meteo.psu.edu/~mann/shared/research/mannetal_science09/mannetal_science09.html), and possible impacts on the behavior of tropical storms and hurricanes (see our '09 Nature article: http://www.meteo.psu.edu/~mann/shared/research/mann_nature09/mann_nature09.html) and the variation in global sea level (see e.g. our 2011 PNAS article: http://live.psu.edu/story/53873) over the last millennium and beyond.

Where does all this lead us? It is very likely that the NH mean temperature has shown much larger past variability than caught by previous reconstructions. We cannot from these reconstructions conclude that the previous 50-year period has been unique in the context of the last 500-1000 years. A larger variability in the past suggests a larger sensitivity of the climate system. The climate sensitivity is a measure how how much the surface temperature changes given a specified forcing. A larger climate sensitivity could mean that the estimates of the future climate changes due to increased levels of green-house gases are underestimated.

Sea level evolution in North Carolina from proxy data (blue curve with uncertainty range). Local land subsidence is already removed. The green curve shows measurements from a nearby tide gauge a reconstruction based on tide gauges from around the world (Jevrejeva et al. 2006, 2008). The red curve shows results from a simple model connecting global temperature with sea level. For the last millennium the sea level curve follows what can be expected from temperature – the two independent reconstructions thus mutually reinforce each other by their consistency. Before 1000 AD there is a discrepancy: warm temperatures in the reconstruction used would lead to rising sea level, but the sea level reconstruction is flat. However, temperature data from before 1000 AD are sparse and less reliable, and lowering temperatures in this period by only 0.2ºC removes the discrepancy. Thus, a possible explanation for the discrepancy is that the temperature reconstruction is a little too warm before 1000 AD.

'A number of tree ring series at high altitudes in the western part of the United States seem to show a prolonged growth spurt that is more pronounced than can be explained with the measured increase in temperature in these regions.'

Frank Lansner skrev:

SRJ foreslog så at måske at vægtning af de enkelte brugte datakilder i Mann 98 (MBH98) er vægtet anderledes, måske dette kan forklare at Mann fik en hockey stick frem trods dette at man blot ser en hockey stick i 2 af de brugte data kilder, vist med rødt:


Jeg svarede tilbage at ja, der er vægtet massivt på de to "røde" serier i Manns arbejde, så det er ikke kun Manns PC program dette handler om.

Så den oprindelige hockeystavs form er altså under ingen omstændigheder et resultat af den statistiske metode.

It is very likely that the NH mean temperature has shown much larger past variability than caught by previous reconstructions. We cannot from these reconstructions conclude that the previous 50-year period has been unique in the context of the last 500-1000 years.

Inspired by previous pseudo-proxy studies we decided to systematically study the skills of seven different reconstruction methods. We included both methods that directly reconstruct the NH mean temperature and methods that first reconstruct the geographical distributed temperatures, The method used by Mann et al. 1998 was included as well as two versions of the RegEM method later used by this group. Perhaps surprisingly the main conclusion was that all the reconstruction methods severely underestimate the amplitude of low-frequency variability and trends (Fig. 1). Many of the methods could reproduce the NH temperature in the calibration period to great detail but still failed to get the low-frequency variability in the reconstruction period right. We also found that all reconstructions methods has a large element of stochasticity; for different realization of the noise or the underlying temperature field the reconstructions are different. We believe this might partly explain why some previous pseudo-proxy studies have reached different conclusions.

It is important to note the two different kinds of errors which are examples of what is known in statistics as ensemble bias and ensemble variance. While the variance may be minimized by taken the average over many reconstructions the same is not true for the bias. Thus, all the reconstruction methods in our study gave biased estimations of the low-frequency variability. We now see the fallacy of the 'hockey team' reasoning mentioned above; if all reconstruction methods underestimate the low-frequency variability then considering an ensemble of reconstructions will not be helpful.

Without endorsing the MBH98 methodology or choice of source data, we were able to apply the MBH98 methodology to a database with improved quality control and found that their own method, carefully applied to their own intended source data, yielded a Northern Hemisphere temperature index in which the late 20th century is unexceptional compared to the preceding centuries, displaying neither unusually high mean values nor variability

First we showed the ex-treme differences in series weightings in MBH98 calculations.
In the NOAMER roster for the AD1400 step, the most heavily weighted site is
Sheep Mountain, Calif. (ca534). Sheep Mountain has a hockey-stick shape
and Mann's algorithm gives it a whopping 390 times the weight in the PC1
of the least weighted series, Mayberry Slough, Ark. (ar052).
....
Almost all the NOAMER series selected for overweighting were of a
single type and from a single researcher, Donald Graybill. The series were
high-altitude bristlecone pine tree-ring chronologies, many of which had
been studied by Graybill and Sherwood Idso as possible examples of CO2
fertilization of tree growth, following a similar study by Lamarche et al. on
Sheep Mountain.

They reported that the anomalous twentieth-century growth was unrelated
to the temperature data from nearby weather stations. In the case of Sheep
Mountain, a weather station had operated within 10 km for nearly thirty
years.

Mann, Bradley and Hughes themselves wrote in MBH99: "A num-
ber of the highest elevation chronologies in the western United States do
appear, however, to have exhibited long-term growth increases that are
more dramatic than can be explained by instrumental temperature trends in
these regions." Later, coauthor Hughes in Hughes and Funkhouser (2003)
would state that these elevated growth rates were a "mystery."

Yet these sites were selected by Mann1 for such high weighting as to
nullify the contributions of all other series in the NOAMER collection put
together. None of the other proxies in MBH98 look like hockey sticks, but
their influence was wiped out. The bristlecone and related series accounted
for more than 99 percent of the weighting in PC1, which in turn was said
to account for 37 percent of the variance in the North America network.
....
In addition to loading hockey-stick shapes into the PC1, the pro-
gramming error also made the bristlecone "signal" in the PC1 appear to be
far more dominant than it really was. It attributed 37 percent of the ex-
plained variance in the entire network to the (incorrect) PC1, thus sug-
gesting the Graybill-Idso sites were the dominant pattern for the whole
continent, while the correctly calculated PC4, to which these sites actually
get weighted, accounts for less than 8 percent of the variance in the
NOAMER network. Thus, what was erroneously argued to be the "dom-
inant" signal in the entire Northern Hemisphere climate turns out to have
been a local phenomenon specific to a group of high-altitude bristlecone
pines...

Surprisingly, given everything that you might read, there is not actually any dispute between the parties on a sufficiently well-specified calculation. On the top left, is a figure from Mann et al's reply to our 2003 article, in which they also obtained very high early 15th century values by excluding bristlecones – that's not how the described the calculation; they described us as having "thrown out" essential data – data that we later determined to be the bristlecones. The top right shows a figure from Bürger et al (2006), confirming and extending our findings that some seemingly innocuous methodological variations yielded 15th century values higher than 20th values. On the bottom left, our 2005 results are re-plotted, together with two scenarios by Mann's frequent coauthors, Wahl and Ammann, in which they varied the methodology and number of retained principal components in the middle and the presence/absence of bristlecones on the right. The Wahl and Ammann results and ours reconcile to 7 9s accuracy, though you'd never know it from the literature. All four groups show that the presence/absence of bristlecones or methodological variations that substantially change their weights alter the 15th century-20th century differential.

Pointen er -som jeg læser det, kan være forkert - at Mann selv havde forsøgt at se hvad der skete når man netop trak Bristlecone data ud... Og han har så lagt resultater ned i en folder "censored" som altså (??) var tilgængelig alligevel.

Så den oprindelige hockeystavs form er altså under ingen omstændigheder et resultat af den statistiske metode.

Jo Bugge, det flade skaft i blandt andet Manns hockeystav er et resultat af den anvendte metode og ikke en afspejling af temperaturer i fortiden.

Bo Christiansen i Bugges citat:

It is very likely that the NH mean temperature has shown much larger past variability than caught by previous reconstructions. We cannot from these reconstructions conclude that the previous 50-year period has been unique in the context of the last 500-1000 years.

OK, men var det ellers ikke det Mann gjorde? Jo, men det viser Bo Christiansen altså, at der ikke er nogen baggrund for at hævde med de anvendte metoder.

The level of warmth during the peak of the MWP in the second half of the 10th century, equalling or slightly exceeding the mid-20th century warming, is in agreement with the results from other more recent large-scale multi-proxy temperature reconstructions by Moberg et al. (2005), Mann et al. (2008, 2009)....

A larger variability in the past suggests a larger sensitivity of the climate system. The climate sensitivity is a measure how how much the surface temperature changes given a specified forcing. A larger climate sensitivity could mean that the estimates of the future climate changes due to increased levels of green-house gases are underestimated.

Og så skal vi lige have misforståelsen af McIntyre og McKitrick's artikel igen selvom jeg har gjort Bugge opmærksom på den før. McIntyre kunne ikke drømme om at sige, at hans replikation af Manns hockeystav med fejlrettede proxydata skulle kunne sige noget som helst om historiske temperaturer.

it was possible to prepare a data base with substantially improved quality control,

The major finding is that the values in the early 15th century exceed any values in the 20th century.

The Mann multiproxy data, when correctly handled, shows the 20th century climate to be unexceptional compared to earlier centuries.

Do we know that whether the 1990s were the warmest decade of the millennium as we so often hear?. In my opinion, no. However, the opposite is also the case: neither do we know that the Medieval Period was warmer than the present. This is because the so-called "proxies" in current use are inconsistent; and, at present, this inconsistency is an insurmountable roadblock to answering the question. Minor changes of even proxy versions from nearby sites can yield opposite medieval-modern differentials.

Jeg vil godt medgive, at McIntyre og McKitrick skulle have fremhævet i abstract, at det er rekonstruktionens ustabilitet, som de viser med artiklen, og at det ikke er et forsøg på en bedre temperaturrekonstruktion. Men det fremgår nu ret klart af artiklen i øvrigt.

Det er vel også menneskeligt set fristende ikonoklastisk at modsige Mann og IPCC i, at nutidens temperaturer er exceptionelle i de sidste 1000 år. Dette opsigtsvækkende resultat af hårrejsende dårlig videnskab, blev jo udbasuneret til alle sider.

CBH: "ja, jeg har lagt mærke til, at Moberg viser en MWP og en LIA - ligesom Mann et al. 2008 og de fleste andre også gør det."

CBH: "Diskussionerne handler om, hvor homogen tidsmæssigt den har været forskellige steder - nogle steder var den varmere end nu, andre steder koldere, nogle steder toppede den i 1200-tallet, andre steder omkring 1000 også videre. "

CBH: "Og problemet er, at hvis du smider så mange proxyer ud, som MM gør.."

CBH: "Så nej, MMs kurve giver bestemt ikke et bedre bud - og det er sådan set ikke et spørgsmål om, hvad "du mener er rimeligt"."

CBH: "- men resultaterne hænger altså ikke på Yamal, som du vedblivende synes at insinuere."

CBH: " Og C&L har bestemt en anden interessant og relevant metodologisk pointe, der muligvis kan afsløre større temperatursvingninger i fortiden. "

CBH: "Der er ingen tegn på noget som helst uhæderligt her"

Hvorfor er det hæderligt at
1) bruge Gaspe data før år 1600 hvor materialet er iflg original forfatterne er tyndbenet? Før 1448 endda kun 2 træer, før 1422 kun ét træ?
2) bruge Bristlecones når alle parter ved at disse ikke repræsenterer temperatur på en brugbar måde?
3) vægte netop mangelfulde Gaspe og bristelcone træserier op til 390 gange mere end f.eks træerne i Arkansas? Hvad er der galt med træerne i Arkansas?
4) at IPCC vedbliver med at bruge videnskabsfolk der bruger Bristlecone data endskønt alle ved de ikke er gode til at repræsentere temperatur?

Frank Lansner skrev:
Lad os se lidt på spørgsmålene i indeværende tråd.
CBH, prøv at svare kort og præcist blot på nogle få issues her:

Hvorfor er det hæderligt at
3) vægte netop mangelfulde Gaspe og bristelcone træserier op til 390 gange mere end f.eks træerne i Arkansas? Hvad er der galt med træerne i Arkansas?

"Jeg kiggede for nogle år siden på alle de temperatur proxies jeg kunne finde på nettet, simpelthen for at få lidt føling med området, vide lidt hvad jeg snakkede om. Et sådant projekt kræver nærmest en PHD afhandling for at gøre alt helt perfekt i enhver henseende, det er jeg udmærket klar over, men den tid og de muligheder har jeg ikke til rådighed - og det kan du så vælge at fokusere på. Man kan bestemt sætte spørgsmålstegn ved præcisionen og sidenhen er jeg blevet opmærksom på endnu flere serier der burde have været med, og et par få der nok ikke burde have været med."

Hvorfor er det hæderligt at
1) bruge Gaspe data før år 1600 hvor materialet er iflg original forfatterne er tyndbenet? Før 1448 endda kun 2 træer, før 1422 kun ét træ?
2) bruge Bristlecones når alle parter ved at disse ikke repræsenterer temperatur på en brugbar måde?
3) vægte netop mangelfulde Gaspe og bristelcone træserier op til 390 gange mere end f.eks træerne i Arkansas? Hvad er der galt med træerne i Arkansas?
4) at IPCC vedbliver med at bruge videnskabsfolk der bruger Bristlecone data endskønt alle ved de ikke er gode til at repræsentere temperatur?

"3) vægte netop mangelfulde Gaspe og bristelcone træserier op til 390 gange mere end f.eks træerne i Arkansas? Hvad er der galt med træerne i Arkansas?"

"ad 3)
For at besvare dette spørgsmål er man nødt til at se på hvordan vægtningen er foretaget. Er det. eks. pga. arealvægtning at man når frem til disse faktorer."

Two days ago, his Penn State bio said he had been "co-awarded" the 2007 Nobel Peace Prize, now merely that he "contributed... to the award" (whatever that means). Over at Wikipedia, they're arguing over ever more unwieldy rewrites. Editing a false legal complaint is trickier but by now someone may have snuck into the DC court clerk's office with a gallon of White-Out and amended "defamation of a Nobel prize recipient" to "defamation of a man who received one of two thousand photocopies of a commemorative thank-you certificate run off at the IPCC branch of Kinko's".

So let's see: A week ago, Michael Mann accused us of damaging his reputation – and seems to have made it a self-fulfilling prophecy. A week ago, he was a "Nobel prize recipient". Now he's not. Great work, Mike!

Christoffer Bugge Harder skrev:
tomt indlæg